1# SPDX-License-Identifier: GPL-2.0-only 2 3config HAS_DMA 4 bool 5 depends on !NO_DMA 6 default y 7 8config NEED_SG_DMA_LENGTH 9 bool 10 11config NEED_DMA_MAP_STATE 12 bool 13 14config ARCH_DMA_ADDR_T_64BIT 15 def_bool 64BIT || PHYS_ADDR_T_64BIT 16 17config ARCH_HAS_DMA_COHERENCE_H 18 bool 19 20config ARCH_HAS_DMA_SET_MASK 21 bool 22 23# 24# Select this option if the architecture needs special handling for 25# DMA_ATTR_WRITE_COMBINE. Normally the "uncached" mapping should be what 26# people thing of when saying write combine, so very few platforms should 27# need to enable this. 28# 29config ARCH_HAS_DMA_WRITE_COMBINE 30 bool 31 32config DMA_DECLARE_COHERENT 33 bool 34 35config ARCH_HAS_SETUP_DMA_OPS 36 bool 37 38config ARCH_HAS_TEARDOWN_DMA_OPS 39 bool 40 41config ARCH_HAS_SYNC_DMA_FOR_DEVICE 42 bool 43 44config ARCH_HAS_SYNC_DMA_FOR_CPU 45 bool 46 select NEED_DMA_MAP_STATE 47 48config ARCH_HAS_SYNC_DMA_FOR_CPU_ALL 49 bool 50 51config ARCH_HAS_DMA_PREP_COHERENT 52 bool 53 54config ARCH_HAS_FORCE_DMA_UNENCRYPTED 55 bool 56 57config DMA_NONCOHERENT_CACHE_SYNC 58 bool 59 60config DMA_VIRT_OPS 61 bool 62 depends on HAS_DMA 63 64config SWIOTLB 65 bool 66 select NEED_DMA_MAP_STATE 67 68# 69# Should be selected if we can mmap non-coherent mappings to userspace. 70# The only thing that is really required is a way to set an uncached bit 71# in the pagetables 72# 73config DMA_NONCOHERENT_MMAP 74 bool 75 76config DMA_REMAP 77 depends on MMU 78 select GENERIC_ALLOCATOR 79 select DMA_NONCOHERENT_MMAP 80 bool 81 82config DMA_COHERENT_POOL 83 bool 84 select DMA_REMAP 85 86config DMA_DIRECT_REMAP 87 bool 88 select DMA_COHERENT_POOL 89 90config DMA_CMA 91 bool "DMA Contiguous Memory Allocator" 92 depends on HAVE_DMA_CONTIGUOUS && CMA 93 help 94 This enables the Contiguous Memory Allocator which allows drivers 95 to allocate big physically-contiguous blocks of memory for use with 96 hardware components that do not support I/O map nor scatter-gather. 97 98 You can disable CMA by specifying "cma=0" on the kernel's command 99 line. 100 101 For more information see <include/linux/dma-contiguous.h>. 102 If unsure, say "n". 103 104if DMA_CMA 105comment "Default contiguous memory area size:" 106 107config CMA_SIZE_MBYTES 108 int "Size in Mega Bytes" 109 depends on !CMA_SIZE_SEL_PERCENTAGE 110 default 0 if X86 111 default 16 112 help 113 Defines the size (in MiB) of the default memory area for Contiguous 114 Memory Allocator. If the size of 0 is selected, CMA is disabled by 115 default, but it can be enabled by passing cma=size[MG] to the kernel. 116 117 118config CMA_SIZE_PERCENTAGE 119 int "Percentage of total memory" 120 depends on !CMA_SIZE_SEL_MBYTES 121 default 0 if X86 122 default 10 123 help 124 Defines the size of the default memory area for Contiguous Memory 125 Allocator as a percentage of the total memory in the system. 126 If 0 percent is selected, CMA is disabled by default, but it can be 127 enabled by passing cma=size[MG] to the kernel. 128 129choice 130 prompt "Selected region size" 131 default CMA_SIZE_SEL_MBYTES 132 133config CMA_SIZE_SEL_MBYTES 134 bool "Use mega bytes value only" 135 136config CMA_SIZE_SEL_PERCENTAGE 137 bool "Use percentage value only" 138 139config CMA_SIZE_SEL_MIN 140 bool "Use lower value (minimum)" 141 142config CMA_SIZE_SEL_MAX 143 bool "Use higher value (maximum)" 144 145endchoice 146 147config CMA_ALIGNMENT 148 int "Maximum PAGE_SIZE order of alignment for contiguous buffers" 149 range 4 12 150 default 8 151 help 152 DMA mapping framework by default aligns all buffers to the smallest 153 PAGE_SIZE order which is greater than or equal to the requested buffer 154 size. This works well for buffers up to a few hundreds kilobytes, but 155 for larger buffers it just a memory waste. With this parameter you can 156 specify the maximum PAGE_SIZE order for contiguous buffers. Larger 157 buffers will be aligned only to this specified order. The order is 158 expressed as a power of two multiplied by the PAGE_SIZE. 159 160 For example, if your system defaults to 4KiB pages, the order value 161 of 8 means that the buffers will be aligned up to 1MiB only. 162 163 If unsure, leave the default value "8". 164 165endif 166 167config DMA_API_DEBUG 168 bool "Enable debugging of DMA-API usage" 169 select NEED_DMA_MAP_STATE 170 help 171 Enable this option to debug the use of the DMA API by device drivers. 172 With this option you will be able to detect common bugs in device 173 drivers like double-freeing of DMA mappings or freeing mappings that 174 were never allocated. 175 176 This also attempts to catch cases where a page owned by DMA is 177 accessed by the cpu in a way that could cause data corruption. For 178 example, this enables cow_user_page() to check that the source page is 179 not undergoing DMA. 180 181 This option causes a performance degradation. Use only if you want to 182 debug device drivers and dma interactions. 183 184 If unsure, say N. 185 186config DMA_API_DEBUG_SG 187 bool "Debug DMA scatter-gather usage" 188 default y 189 depends on DMA_API_DEBUG 190 help 191 Perform extra checking that callers of dma_map_sg() have respected the 192 appropriate segment length/boundary limits for the given device when 193 preparing DMA scatterlists. 194 195 This is particularly likely to have been overlooked in cases where the 196 dma_map_sg() API is used for general bulk mapping of pages rather than 197 preparing literal scatter-gather descriptors, where there is a risk of 198 unexpected behaviour from DMA API implementations if the scatterlist 199 is technically out-of-spec. 200 201 If unsure, say N. 202